﻿#region Copyright (c) 2003 - 2008, Andreas Mueller
/////////////////////////////////////////////////////////////////////////////////////////
// 
// Copyright (c) 2003 - 2008, Andreas Mueller.
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// which accompanies this distribution, and is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// Contributors:
//    Andreas Mueller - initial API and implementation
//
// 
// This software is derived from software bearing the following
// restrictions:
// 
// Copyright (c) 1994
// Hewlett-Packard Company
// 
// Permission to use, copy, modify, distribute and sell this software
// and its documentation for any purpose is hereby granted without fee,
// provided that the above copyright notice appear in all copies and
// that both that copyright notice and this permission notice appear
// in supporting documentation.  Hewlett-Packard Company makes no
// representations about the suitability of this software for any
// purpose.  It is provided "as is" without express or implied warranty.
// 
// 
// Copyright (c) 1996,1997
// Silicon Graphics Computer Systems, Inc.
// 
// Permission to use, copy, modify, distribute and sell this software
// and its documentation for any purpose is hereby granted without fee,
// provided that the above copyright notice appear in all copies and
// that both that copyright notice and this permission notice appear
// in supporting documentation.  Silicon Graphics makes no
// representations about the suitability of this software for any
// purpose.  It is provided "as is" without express or implied warranty.
// 
// 
// (C) Copyright Nicolai M. Josuttis 1999.
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
// 
/////////////////////////////////////////////////////////////////////////////////////////
#endregion

using NStl.SyntaxHelper;
using NUnit.Framework;
using NStl.Linq;
using NUnit.Framework.SyntaxHelpers;
using System.Collections;
using System.Collections.Generic;
using NStl.Iterators.Support;

namespace NStl.NUnit.AlgorithmFixtures.NthElement
{
    [TestFixture]
    public class NthElementFixture
    {
        private static List<int> v;
        private static ListTIterator<int> nth;
        private const int distNth = 4;
        [SetUp]
        public void SetUp()
        {
            v = new List<int> {7, 2, 6, 9, 3, 0, 8, 4, 1, 5};
            nth = v.Begin() + distNth;
        }
        // at nth the element that would be there after full sort
        // all elements before are less
        // all elements after are greater
        [Test]
        public void NthElementIsSameAsIfRangeWasSorted()
        {
            Algorithm.NthElement(v.Begin(), nth, v.End());
            Assert.That(nth.Value, Is.EqualTo(distNth));
        }
        [Test]
        public void BeforeNthElementIsOnlyLess()
        {
            Algorithm.NthElement(v.Begin(), nth, v.End());
            ListTIterator<int> i =
                Algorithm.FindIf(v.Begin(), nth, Bind.Second(Compare.Greater<int>(), nth.Value));

            Assert.That(i, Is.EqualTo(nth));
        }
        [Test]
        public void AfterNthElementIsOnlyGreater()
        {
            Algorithm.NthElement(v.Begin(), nth, v.End());
            ListTIterator<int> i =
                Algorithm.FindIf(nth, v.End(), Bind.Second(Compare.Less<int>(), nth.Value));

            Assert.That(i, Is.EqualTo(v.End()));
        }

        [Test]
        public void NthElementIsCorrectIfRangeIsAllreadySorted()
        {
            List<int> sorted = new List<int> {0, 1, 2, 3, 4, 5, 6, 7, 8};
            ICollection expected = sorted.ToArray();

            Algorithm.NthElement(sorted.Begin(), sorted.Begin() + 4, sorted.End());

            Assert.That(sorted, Is.EqualTo(expected));
        }
        [Test]
        public void StartIteratorIsEqualToNthIterator()
        {
            ListTIterator<int> nthIsBegin = v.Begin();
            Algorithm.NthElement(v.Begin(), nthIsBegin, v.End());
            Assert.That(nthIsBegin.Value, Is.EqualTo(0));

        }
        [Test]
        public void EndIteratorIsEqualToNthIterator()
        {
            // this test is a pure boundrary condition test. We simply test
            // that nothing crashes and that the range
            // does not gain or loose any elements.
            ListTIterator<int> nthIsEnd = v.End();
            ICollection expected = v.ToArray();
            Algorithm.NthElement(v.Begin(), nthIsEnd, v.End());

            Assert.That(v, Is.EquivalentTo(expected));
        }
    }
}
